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.Dec. 23, 1952 F. JAUBERT APPARATUS FOR COOLING AND DEHYDRATING AIRFiled July 31, 1947 5 Sheets-Sheet l r m. a z Z Z V A NM M 4| m & ,7 J RE m z m a Q Afi/ Q \k \lu \\M U "A W Sq Dec. 23, 1952 G. F. JAUBERTAPPARATUS FOR COOLING AND DEHYDRATING AIR File d'July 31, 1947 3Shqets-Sheet 5 Patented Dec. 23, 1952 OFFICE APPARATUS FOR COOLING ANDDEHYDRATING AIR Georges Francois Jaubert, Paris, France Application July31, 1947, Serial No. 764,946 In France December 18, 1939 4 Claims.

My invention relates to' processes and corresponding devices, intendedfor producing large quantities of cold air.

When desiring to secure a more or less intensive production of cold air,one generally draws the air from the atmosphere and sends it onto acluster of pipes within which is circulated a brine or salt solution,cooled by means of an ice' machine, the refrigeration then resultingfrom both the conductibility and the convection.

Sometimes one attempts to increase the intensity of the cold thusobtained by evaporating, within the cluster of pipes, a suitablerefrigerant, such as, for instance, anhydrous liquid ammonia, liquidcarbonic acid, etc. obtained generally remains unsatisfactory, due tothe fact that, on the one hand the cluster of refrigerating pipesquickly covers itself with frost which reduces its thermicconductibility, while,

on the other hand the installations using that process are so bulky thatthey do not afford the possibility of treating large quantities of air.Moreover, the degree of cooling of the air by means of the process underconsideration is fixed and cannot be varied. It is, once for all,determined only by the nature of the refrigerant used, and it does notgive the possibility of obtaining quick variations (still lessinstantaneous variations) of the degree of refrigeration of the air.

The process described herein has for an object to eliminate thosedrawbacks: It consists essentially in first compressing the air intendedfor refrigeration, and then drying it and furthermore expanding it, theimportance of the expansion varying with the degree of cold to beobtained: thus is realised an economical, and practically instantaneousproduction of large quantities of cold air, the refrigeration of whichcan be obtained with the simultaneous performance of an external workand a corresponding recovery of energy: a circumstance which brings downthe production cost of that cold air. I

My invention thus results in an economical production of cold air,at'very low temperature. According to the tests which I have made thecooling of wet air consumesan amount ofenergy far more considerable thandoes; the cooling of dry air. If one desires, for instance, to bringdown to C. the temperature of one cubic meter of air taken at C. in thestate of-saturation and containing, for instance, 25jgr. of water vapor,the calories needed amount to 22.707, of which only are utilized for therefrigeration of air, while 79% are consumed for the refrigera- Theefliciency thus tion of the water and its elimination in the form offrost.

A calculation shows that the refrigeration of dry air taken at 25 C.down to 0 C. necessitates the use of only 5.5 calories per kilogram,while the refrigeration of water vapor, between the same limits of 25 C.and 0 C. necessitates the use of 690 calories per kilogram, i. e. 125times more than for the air. The appended drawings illustrateschematically a form of my invention, taken as an instance, of aninstallation intended for economically producing large quantities ofcold air:

Fig. 1 is a general diagram of the installation,

Fig. 2 schematically represents a sectional view of a drying apparatusgiven as an instance,

Fig. 3 and 4 schematically represent improved forms of the installationshown in Fig. 1.

Fig. 5 is a plane view corresponding to the Fig. 4.

The installation comprises a compressor I (Fig 1), of the rotary typefor instance, coupled for instance with an appropriate electric motor 2.That compressor sucks the air directly from the atmosphere, preferablythrough a dust filter, and it compresses that air, through a piping 3,into a suitable cooler 4 provided with a draining device and connectedwith a drying apparatus, composed for instance of two reservoirs 5 and 6containing a suitable material for damp absorption (said material beingpreferably regenerable in situ), such as, for instance, the

product which is known by bagel.

The reservoirs 5 and 6 are connected by a common pipe 1, from which isstarted a pipe 8, extended, through a cooler l5,.to an expansion turbine9, preferably keyed onto the shaft of the electric motor 2. The exhaustpipe ID of the turbine 9 is connected to the apparatus intended for theutilization. of the cold air. i

As my process aims at producing, before all, very large amounts of coldair at as. low aco'st as possible, and as the only real expensesinvolvedreside in those resulting from the air compression, it is indispensableto compress it only to the least possible extent: for instance by only 2or 3 effective kg. per cm?, so as to obtain a temperature of at theexhaust. :I therefore take care of avoiding all unnecessary compression,and I consequently eliminate all 1305-- sibilities of any losses ofpressure head in the piping as well "as in-the drying iapparatus,'be'cause :an eifective loss of pressure. head amounting to only 0.5 kg. to11kg. per cm. would conthe name of Carsiderably influence the ratio ofthe pressures before and after the expansion, with the result that theproduction of cold would fall down accordingly.

In consideration of the large volume of air undergoing treatment, aswell as of the almost :absolute degree of desiccation which is desired,before the expansion takes place, it is necessary to develop the surfaceof the dehydrator, and to use the absorbent material in the form ofsmall grains. If those grains were simply thrown into high drying towers(of some 5 or meters height for instance), they would oppose a very highresistance to the flow of air.

Consequently, the general information on the above describedinstallation should be completed by some data re: the insidedispositions of the drying apparatus which have been designed in orderto reduce the loss of pressure head.

For that purpose, each one of the generators 5 and 6 containing the dampabsorbent (Garbagel for instance) comprises, as shown in Fig. 2, anenvelope l6 containing, within its walls, a stack made by the piling upof several sections or rings [1, l8 concentric to the envelope, the saidsections having their walls provided with a large number of holes andcontaining the absorbent material, such as Carbagel.

The central section of the stack 18 (Fig. 2), is connected to the pipe29 bringing the air to the drying apparatus. The head 2! which closesthe upper extremity of the envelope I6 is set at a proper distance ofthe drying stack, 50 that a space is left therein, between the stack andthe head, for a chamber 22 wherefrom starts the outlet pipe 23.

Because of that disposition, the wet air which enters the centralsection of the stack IS flows from that stack through the many holes ofits walls, and, after having run through the filling of carbagel,escapes through the wall 17, similarly perforated, for gathering on thechamber 22. That disposition results in a suitable dehydration of theair, while it opposes only a relatively low resistance to itscirculation.

The dehydration battery 56 preferably includes :a device intended forthe regeneration of the carbagel contained within; it may offer anysuitable disposition, and comprise an inlet air pipe H running acrossthe. regenerating heater l2 which can be connected to the one or theother of the reservoirs 5 and 5, or to both of them (Fig. 1). The saidreservoirs comprise exhaust pipes shown in I3 and [4 (Fig.1) and eachone of those capacities can be isolated from the all compressed inletpipe 3 and from the pipe 8 leading to the expansion turbine 9.

From the compressor l the air is at first led, through the pipe 3, tothe cooler 4 which cools it down approximately to the ambienttemperature; afterwards it is sent across the one or the other of thedrying reservoirs 5, 6, in which the air abandons the water it contains.Once it has been brought back to the ambient temperature in the coolerl5, the air is sent to the expansion turbine 9, wherefrom it comes outat very low temperature before being sent to the utilization apparatus.As the air expands in the turbine 9, it produces therein a useful work,which can, for instance, be utilized for running the compressor I: inwhich case the electric motor 2 is called upon to supply only thenecessary complement of power eventually needed.

Thus is obtained, at the outlet pipe 10 of the turbine 9, refrigeratedair, the degree of cooling of which can be modified at any time, simplyby varying the air pressure before its expansion, or the exhaustpressure, which may be lower than the atmospheric pressure. Indeed thegreater is the ratio between the inlet pressure and the outlet pressure,and the colder is the air leaving the apparatus.

For obtaining :a higher degree of cold it is possible, after havingdried all the air, to send part of it to a supercompressor of anysuitable type which gives it an excess of pressure; and after havingbrought down that fraction of air to the ambient temperature, to expandit in a piston motor with performance of external work, the expansion inthat case coming nearer the pure adiabatic expansion than would do theexpansion in a turbine.

Thus can be obtained dry and very cold air, which is afterwards mixedwith the remainin fraction of the air which has been compressed onlyonce. Thus it is easy to obtain the total possible range of cold, whileoperating on large volumes of air. Drying under pressure releases aproportion of the heat contained in the wet air, so that this air underpressure is warmer when leaving the drying apparatus than when enteringit: it generally reaches the turbine at a temperature of +25 C., acondition which may beundesirable when very cold air must be ob tainedat the exhaust of the turbine.

To obviate that inconvenience, it is possible to use anothercharacteristic of the invention, according to which the air is firstcooled, for instance down. to 0 or a lower temperature, before enteringthe expansion turbine, by means for instance of an ordinary ice machine(ammoniac, or sulfurous gas or carbonic acid machine, etc.) Theefliciency and the yield in cold air are so much improved when doing so,that they largely compensate not only for the acquisition and operationcosts of the supplementary material, but also for the excess timenecessary for putting in service the ice machine.

In the same line of progress my invention involves an improved process,which consists in directly or indirectly effecting a heat exchangebetween a part or the totality of the air leaving the expansion turbineand the totality or a fraction of the air entering the said turbine, inorder to refrigerate and to dry the compressed and to dry it, partiallyor totally, before it enters the turbine, with eventually no use ofexternal chemical means or devices, thus securing a simplification ofthe system in which the refrigeration precedes the expansion.

In carrying out the said process, I lead the totality or a part only ofthe cold air leaving the turbine into a heat exchanger (tubularexchanger or indirect acting air cooler, brine cooler or direct actioncold accumulator), wherein it abandons its cold, either directly(tubular exchanger, cold aocumulator), to the whole or to a part only ofthe air under pressure which is going to enter the turbine, eitherindirectly through the intermediary of a brine air cooler, i. e. bymeans of an unoongealable brine which will have the same effect as theexchanger just mentioned or as a cold accumulator of a Known type.

That portion of the air thus expanded, but a little reheated whilepassing through the exchanger, is mixed, in principle, with the restflows towards the utilization.

As it is plain, the direct acting exchanger, or

the indirect action brine air cooler, or else the cold accumulator, aresimply inserted in by-pass on the path of the exhaust cold air flowingtowards its place of utilization.

For regulating the degree of intensity of that preliminaryrefrigeration, it is possible to act either on the air presure whenadmitted into the turbine (i. e. on the air compressor), or on thedegree of the vacuum at the exhaust of the turbine, or on both factorsat the same time. It is also possible to act on the amount of cold airwhich is by-passed by the exchanger.

From an economical point of view, the latter system offers the advantagto eliminate the ice machine, and this compensates largely for thesupplementary work imposed on the compressor in order to maintain, atthe turbine exhaust, a determined and rather low temperature (of theorder of 50 to 75 under zero).

The gain in efficiency resulting from that refrigeration effected priorto the expansion, results also from the fact that the compressed airthus cooled looses in the exchanger an important part of the water thatit can still contain: and that permits to use only preliminary chemicalair .dryers of small importance instead of the very large apparatusutilized till now and which have been described above.

Fig. 3 illustrates a form of my invention and an instance of aninstallation based on the last mentioned process. Acompressor 2| forinstance, of the rotary type, is keyed on the shaft of a motor 22, forinstance electrical. That com pressor sucks the air directly from theatmosphere through its piping 23, and discharge the compressed airthrough its pipe 24, its cooler 25 and the pipe 21 in a cooler 29. Thatair, once it has been cooled in the cooler 26, is brought back by thepipe 28, through an air dryer 29, into an expansion turbine 39,preferably keyed on the other end of the shaft of the electric motor 22.After having passed through the turbine, the air. is led by a pipe 3| tothe apparatus in which it'will be utilized; and on the pipe ispreferably disposed a valve 32, around which a bypass communicates, bymeans of a valve 36, with a coil placed in a brine air cooler 34. Thesaid air cooler communicates with the heat exchanger 26 through a pipe38 in a closed cycle in which is inserted a brine circulating pump 33.At the base of the tube coil through which the air is circulated, in thecooler 26, is installed a draining valve 39.

Innormal operation, the valve 32 is closed and the valve 36 open; theair leaving the turbine 39 through the pipe 3| is sent through the pipe35 and the open valve 36 into the brine refrigerator 34, where itreleases a part of its low temperature to the brine circulated by thepump 33 and the pipe 38 in the cooler 29. The whole of the air deliveredby the compressor 2| into the cooler 26, through the pipe 21, is thuscooled by the effect of the said brine, and it releases a part of thecondensed vapor it contained herein; this latteraccumulates, in the formof liquid water, at the base of the cooler 26, wherefrom it can be fromtime to time drained by means of the draining valve 39. That air is thensuitably dried by the air dryer 29 before it arrives to the expansionturbine 30.

My invention provides for the improvement of the above describedprocesses, by the use of thermo-regenerable dehydrants, which make itpossible to obtain, according to my observations, a degree ofdesiccation, which becomes more pronounced, as the temperature at whichthe drying operation is carried out decreases and even at temperatureslower than 0 C.

The process thus improved consists, on the one hand: in using two dryingdevices, one working at the ambient temperature, and the other at atemperature of the order of 0 or even under 0; on the other hand, inutilizing, for the regeneration of the regenerable dehydrant, the heatdeveloped by the compression of the air, so as to make use of all thepossibilities offered by the process and to render it as economical aspossible.

The two Figures 4 and 5, the corresponding components of which have beengiven the same reference numbers, illustrate schematically anarrangement of a plant carried out according to the above process: Fig.4 shows a complete elevation view of such an installation, and Fig. 5shows a simplified plan of the same.

When leaving the compressor which is a part of thecompressor-motor-turbine group numbered 4|, the air under pressure,heated by the compression work, passes through a tubular exchanger 43,which is a cooler and a recuperator, wherein the air gives up itscalories to the regenerative air needed for the reactivation of theregenerable dehydrant, the so-called regenerative air being sucked inthe outside atmosphere and blown into the exchanger 43 by the blower 50.

If the temperature of the regenerative air would not suffice forsecuring a complete reactivation of the dehydrant used (for instance ifthe compressor should compress only at too small a pressure), anelectric heater 5|, similar to the heater mentioned with regard to Fig.1, supplies the balance of calories. The heating resistance can,moreover, be provided with means for several rates of heating, in orderto be able, by itself alone and with the help of the blower 50, toassure the complete reactivation of the dehydrant utilised when theturbo-compressor is at rest.

When leaving the exchanger 43, which recuperates the heat of thecompression, the compressed air passes through a tubular cooler 44,supplied with cold water, then in a drainer-condenser-oil separator 45,of a known type, and finally through the main dryer 46, which containsthe regenerable dehydrant (carbagel, silicagel, alumina etc.) working atthe ambient temperature.

When leaving the air dryer 49, the air is already almost completelydesiccated, but it has been slightly heated; it is then passed through atubular cooler 41, supplied also by cold water, wherefrom the airexhausts at a temperature of about 15 C.

The compressed air then enters a heat exchanger 48, in which it iscooled to a temperature lower than 0 C., generally between -5 C. and 10C., by exchange of heat with very cold air coming from the exhaust ofthe expansion machine T of the group 4|, machine which may be, forinstance, of the turbine type, the sliding vane type, or the pistontype. After leaving the exchanger 49. the cooled compressed air is ledto a second drier 49, in which it is further dried, and which it leavessubstantially completely dry to enter a pipe 60, connecting the drier 49to the inlet of the expansion machine T. Another pipe 52 connects thedrier 49 to the heater 5| intended for the regeneration.

The substantially completely dry air entering the expansion machine Texpands therein, and temperature becomes very low of the order of C. forinstance. The exhaust from, the

expansion machine is connected to an utility line U, directly through avalve 62, and indirectly through a valve 54, the cooling line of theexchanger 43, and a valve or cook 55. Such an arrangement permits ofobtaining very cold and dry air, in a short time after the starting ofthe installation, and of rapidly regulating the temperature of this air.

On setting the installation going, the valve 42 is closed, the valve 54is open, and the cock 55 is positioned so as to make the line 56communicate with the pipe 57 with direct exhaust into the atmosphere;under these conditions the entire cold air produced by the expansionturbine T is used to cool the compressed air coming from the cooler 51,in such a way that the air which is led to the admission or" theexpansion turbine is rapidly cooled and that, consequently, the airfurnished by this turbine rapidly reaches the desired low temperature,for example 80 degree C. The valve 52 is then opened and the cook 55 ispositioned so as to make the line 56 communicate with the appliance U.The temperature of the appliance air is regulated by manipulation of thevalves 42 and Fa l, and cook 55; the lowest temperature is obtained whenthe cock'55 evacuates into the pipe and when only the air coming fromthe valve 22 is used.

In another form of embodiment, there is no second drier 49, and thecooled compressed air leaving the exchanger 58 is directly brought tothe pipe 69, and led therethrough to the inlet of the expansion machineT.

An installation as the one of Figs. 4 and 5 applies easily to theproduction of rapid and even instantaneous variations of the temperatureof the dry and cold air sent towards the utilization U, by means of aquadruple regulation, bearing on the following elements: (1) regulationof the pressure of the compressed air operating the expansion motor; (2)regulation of the pressure in the exhaust pipe of the expansion motor,by lowering the said pressure to a value even inferior, if necessary, tothe atmospheric pressure; (3) regulation of the mixture, in definiteamounts, of the very dry and cold air (80 to 100 C.) which leaves theexpansion motor, with the expanded air similarly dry, but by far not socold, which leaves the return of the counter-flow exchanger, whichlatter receives the whole or a part of the exhaust from the expansionmotor, and which serves to cool the compressed air supplying the 2nddryer; at last: (4) regulation of a mixture made of the air speciallydried, by whatever means but not necessarily cooled, with very cold airleaving the expansion motor.

What I claim is:

1. An installation for the conversion of large quantities of starting oratmospheric air into very dry gaseous air at temperatures rapidlyregulable between the limits of neg. 50 and neg. 100 deg. C., comprisinga compressor for converting the starting air into compressed air, meansfor first cooling the compressed air for converting the compressed airinto compressed air cooled to a temperature of the order of thetemperature of the starting air, means for drying by a dehydrating agentregeneratable by heat for converting the said cooled compressed air intosubstantially completely dry air, means for eifecting a second coolingof substantially completely dry air, including a heat exchanger forconverting the said substantially completely dry air into cold dry airat a temperature of at least neg. deg. C., an expansion machine forconverting the said cold dry air into very cold dry air at a temperatureof the order of neg. 50 to neg. deg. C., an utility line to receive apart of said very cold dry air and deliver said very dry gaseous air,means for deriving another portion of said very cold dry air andcirculating the said very cold dry air through said heat exchanger tocoact with said second cooling means and convey it to said utility line,and means for regulating the magnitude of said quantities of air wherebysaid very dry gaseous air is brought to the desired temperature.

2. An installation for the conversion of large quantities of starting oratmospheric air into very dry gaseous air at temperatures rapidlyregulable between the limits of neg. 50 and neg 100 deg. C., comprisinga compressor for converting the starting air into compressed air, meansfor first cooling the compressed air for converting the compressed airintocompressed air cooled to a temperature of the order of thetemperature of the starting air, means for drying by a dehydrating agentregeneratable by heat for converting the said cooled compressed air intosubstantially completely dry air, means for effecting a second coolingof said completely dry air, including a heat exchanger with a coolingline for converting the said substantially completely dry air into colddry air at a temperature of at least neg. 10 deg. C., an expansionmachine for converting the said cold dry air into very cold dry air at atem perature of the order, of neg. 50 to neg. 100 deg. C., and means forconnecting the exhaust from said expansion machine to an utility line,last said means including a direct connection through a regulable valveand an indirect connection successively through a second regulablevalve, the cooling line of said heat exchanger, and a third valve.

3. An installation for the conversion of large quantities of starting oratmospheric air into very dry gaseous air at temperatures rapidlyregulable between the limits of neg. 50 and neg. 100 deg. C., comprisinga compressor for converting the starting air into compressed air, meansfor first coolin the compressed air for converting the compressed airinto compressed air cooled to a temperature of the order of thetemperature of the starting air, means for drying by a dehydrating agentregeneratable by heat for converting the said cooled compressed air intodehydrated compressed air, means for effecting a second cooling of saiddehydrated compressed air, including a heat exchanger for converting thesaid dehydrated compressed air into cold dry air at a temperature of atleast neg. 10 deg. C., means for effecting a second drying by adehydrating agent regeneratable by heat for converting the said cold dryair into substantially completely dry air, an expansion machine forconverting the said substantially completely dry air into very cold dryair at a temperature of the order of neg. 50 to neg. 100 deg. C., anutility line to receive a part of said very cold dry air and deliversaid very dry air, means for deriving another part of said very cold dryair and circulating the said derived air through said heat exchanger tocoact with said second cooling, and deliver it to said utility line, andmeans for regulating the magnitude of said parts whereby said very dryair is brought to the desired temperature.

4. An installation for the conversion of large quantities of starting oratmospheric air into very dry gaseous air at temperatures rapidlyregulable 9 between the limits of neg. 50 and neg. 100 deg. C.,comprising a compressor for converting the starting air into compressedair, means for eflecting a first cooling the compressed air forconverting the compressed air into compressed cooled air to atemperature of the order of the temperature of the starting air, meansfor drying by a dehydrating agent regeneratable by heat for convertingthe said cooled compressed air into dehydrated compressed air, means foreffecting a second cooling of the dehydrated compressed air including aheat exchanger with a cooling line for converting the said dehydratedcompressed air into cold dry air at a temperature of at least neg. 10deg. C., means for effecting a second drying of the cold dry air by adehydrating agent regeneratable by heat for converting the said cold dryair into substantially completely dry air, an expansion machine forconverting the said substantially completely dry air into very cold dryair at a temperature of the order of neg. 50 to neg. 100 deg. C., andmeans for connecting the exhaust from said expansion machine to anutility line, last said means including a di- .10 rect connectionthrough a regulable valve and an indirect connection successivelythrough a second regulable valve, the cooling line of said heatexchanger, and a third valve.

GEORGES FRANQOIS JAUBERT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

